---
title: "Rails 5 changed Active Job default adapter to Async"
description:
  "The default Active Job adapter has been changed to Async from Inline in Rails
  5."
canonical_url: "https://www.bigbinary.com/blog/rails-5-changed-default-active-job-adapter-to-async"
markdown_url: "https://www.bigbinary.com/blog/rails-5-changed-default-active-job-adapter-to-async.md"
---

# Rails 5 changed Active Job default adapter to Async

The default Active Job adapter has been changed to Async from Inline in Rails 5.

- Author: Mohit Natoo
- Published: March 29, 2016
- Categories: Rails 5, Rails

Active Job has built-in adapters for multiple queuing backends among which two
are intended for development and testing. They are
[Active Job Inline Adapter](http://api.rubyonrails.org/classes/ActiveJob/QueueAdapters/InlineAdapter.html)
and
[Active Job Async Adapter](http://api.rubyonrails.org/classes/ActiveJob/QueueAdapters/AsyncAdapter.html).

These adapters can be configured as follows.

```ruby

# for Active Job Inline
Rails.application.config.active_job.queue_adapter = :inline

# for Active Job Async
Rails.application.config.active_job.queue_adapter = :async

```

In Rails 4.x the default queue adapter is `:inline`. In Rails 5 it has
[been changed to](https://github.com/rails/rails/commit/625baa69d14881ac49ba2e5c7d9cac4b222d7022)
`:async` by DHH.

## Asynchronous Execution

In case of `inline`, as the name suggests, execution of the job happens in the
same process that invokes the job. In case of Async adapter, the job is executed
asynchronously using in-process thread pool.

`AsyncJob` makes use of a
[concurrent-ruby](https://github.com/ruby-concurrency/concurrent-ruby) thread
pool and the data is retained in memory. Since the data is stored in memory, if
the application restarts, this data is lost. Hence, `AsyncJob` should not be
used in production.

## Running in future

`AsyncJob` supports running the job at some time in future through
`perform_later`. `Inline` executes the job immediately and does not support
running the job in future.

Both Active Job Async and Active Job Inline do not support configuring
priorities among queues, timeout in execution and retry intervals/counts.

## Advantage of having Async as default adapter

In Rails 4.x where `Inline` is the default adapter, the test cases were
mistakenly dependent on job's behavior that happens synchronously in
development/testing environment. Using `Async` adapter ,by default, will help
users have tests not rely on such synchronous behavior.

It's a step closer to simulating your production environment where jobs are
executed asynchronously with more persistent backends.

Consider an example, where in an e-commerce site upon every order placed an
email is sent.

```ruby

test "order is created successfully" do
  # Code to test record in orders table is created
end

test "order email is sent" do
  # Code to test order email is sent
end

```

The process of sending email can be part of a job which is invoked from an
`after_create` callback in `Order` model.

```ruby

class Order < ActiveRecord::Base

  after_create :send_order_email

  def send_order_email
    # Invoke the job of sending an email asynchronously.
  end

end

```

When `Inline` adapter is used, any wrongly configured email settings will cause
both the above tests to fail. This is because the process of sending the email
happens within the process of order creation and any error in sending the email
would kill the process if unhandled.

## Links

- [Human page](https://www.bigbinary.com/blog/rails-5-changed-default-active-job-adapter-to-async)